animism

Animism is the oldest known type of belief system in the world. It is still practiced in a variety of forms in many traditional societies. Animism is used in the anthropology of religion as a term for the belief system of many indigenous tribal peoples.

source wikipedia

Animism is the doctrine or theory of the soul. In current language the term has a twofold signification:
I. PHILOSOPHICAL–the doctrine that the soul is the principle of life in man and in other living things. As applied to man it embodies the essence of spiritualistic as opposed to Materialistic philosophy.
II. ETHNOLOGICAL–a theory proposed in recent years to account for the origin and development of religion. As such it is known as the Soul or Ghost-theory of religion.

Germanic and Roman culture survived Christianity and was embedded in the literature in the Middle Ages. Both Germanic and Christian culture believed in invisible spiritual agencies like elves or germanic lore, whose venomous shots need purging or demons to be exorcised as in the Christian cosmology. natural ingredients such as herbs contained virtues or powers that could be activated for healing (example the herb aelfthone or elf afflictions). In the pagan system in relation to the Christian view, the herbs were made potent by appeals to God.
Third, in both traditions words have power to transform natural objects. Germanic charms invoked the invisible powers in nature for the purpose of healing: the word of a priest transform bread and wine into body and blood, and it is not surprising that so many remedies prescribe masses said over herbs to invoke their natural potency to cure illnesses taht may have an invisible or spiritual cause.

-source- Tradition and Diversity: Christianity in a World Context to 1500. Karen Louise Jolly